38 DEPARTMENT BULLETIN 863, U. S. DEPT. OF AGFdCULTURE. 



KEY TO COMMON KINDS OF TREES. 1 



The following key is intended only as a guide in the identification of the 

 more common kinds of trees. It is based on prominent, distinctive character- 

 istics which can readily be observed by those who have no special training in 

 botany. Most of the terms used require no explanation. 



To use the key, decide first, by an examination of the leaf, in which of the 

 following seven sections your tree belongs ; then turn to that section, and from 

 the descriptions there given determine what kind of tree it is. 



Section. 

 Trees with needles or scale-like leaves, mostly evergreens, bearing cones_ I 

 Trees with broad leaves : 

 Leaves simple — 



Alternately attached to twigs — 



With toothed edges II 



Edges neither toothed nor notched III 



Opposite on twigs — 



With toothed edges IV 



Edges neither toothed nor notched V 



Leaves compound — 



Alternately attached to twigs VI 



Opposite on twigs VII 



THE CONIFEROUS 2 TREES. 



I. Trees with Needles ok Scale-like Leaves, Mostly Evergreen, Bearing 



Cones. 

 A. Leaves needle-shaped : 



(1) Leaves clustered — 



(a) Leaves long, from 1 to 18 inches, 2 to 5 in a cluster. Cones 

 large, with many thick, woody scales (Pinus) Pine. 



(&) Leaves short (less than 2 inches long) in brush-like clus- 

 ters of 12 to 40 ; falling off in winter. Cones very small, 

 with thin scales ; remaining on tree for one or more 

 seasons (Larix) Larch. 3 



(2) Leaves single — 



(a) Leaves scattered around twigs; falling off when dry or 

 dead. Cones elongated, with thin scales. Twigs rough- 

 ened by leaf -scars. 



(x) Leaves stiff, often sharp-pointed and more or 



less four-sided (Picea) Spruce. 



(y) Leaves soft, Hat, rounded, or notched at ends, the 

 bases abruptly contracted into thread-like 



stems (Tsuga) Hemlock. 



(6) Leaves in two distinct rows, one on each side of the twig; 

 falling off in late autumn or winter. Cones small, 

 ball-like (Taxodium) Bald cypress. 



1 This key and the following tree descriptions are by William II. Lamb, Scientific 

 Assistant in Dendrology, Forest Service. 



2 Cone-bearing. 



3 The larches are peculiar in having single, scattered leaves on the new or terminal 

 twitfs produced each season. These should not be mistaken for the " single " leaves 

 borne throughout by other kinds of evergreens. 



